This is an update of an article I first put out as a blog post in 2016.

Have you heard the term “opposition reflex” used in dog training? It’s a common phrase.

In 2016 I got to wondering whether the opposition reflex was really a reflex. (Quick answer: “No.” )

Here’s some context. I gathered the following quotes about the “opposition reflex” from a selection of dog training articles.

• “The dog’s opposition reflex [is the] instinctive reaction to push against a push.”
• “Dogs have a natural resistance to pressure called the opposition reflex.”
• “If dogs are pulled in one direction, they will automatically pull in the other direction.”
• “The opposition reflex is your dog’s natural instinct to resist pressure.”

After finding dozens of claims such as those above, I started looking for the term “opposition reflex” in lists of actual reflexes. I looked in biology, physiology, and behavior analysis textbooks. I looked in scholarly articles.

Results: practically nothing.

Virtually all mentions of the so-called “opposition reflex” are in lay articles about dog and horse training. So where did this term come from and why do we use it? It’s not in the textbooks.

What Is a Reflex?

To know whether the “opposition reflex” is truly a reflex, we need to know what reflexes are. Here are some definitions from biology, psychology, and neuroscience by way of applied behavior analysis.

A reflex is an automatic response to nerve stimulation.

(Alters, 2000)

Reflex, noun. Any of a number of automatic, unlearned, relatively fixed responses to stimuli that do not require conscious effort and that often involve a faster response than might be possible if a conscious evaluation of the input were required.

APA Dictionary of Psychology

Reflexes are involuntary, discrete, and consistent behaviors. One neuroscientist states that they can be thought of as “atoms of behavior.”

(Baars, 2003)

In general, reflexes are not under operant control, although some can be influenced operantly. They are respondent behaviors, and the important thing to remember are that they are automatic.

Some examples of reflexes in dogs are:

• the scratch reflex: dog’s leg kicks when you scratch them on certain parts of the body;
• the acoustic startle response: a reflex common to mammals where the body responds to a sudden sound with a rapid extension, then flexion of several muscles:
• the palpebral reflex: dog blinks when the skin below the corner of the eye is tapped;
• the stretch or myotatic reflex: a reflex common to most mammals in which a muscle that is stretched will contract;
• the righting reflex: a group of motor functions that help the animal stay in the proper orientation and posture (right side up)
• the vestibulo-ocular reflex: the eyes move to stabilize images when the head moves;
• the pupillary light reflex: the pupil of the dog’s eye contracts when a bright light is shined on it;
• the withdrawal reflex: dog pulls foot away when toe is pinched
• the rooting and suckling reflexes in very young puppies;
• and many more.

The ones in bold have to do with balance and I’ll discuss them more below.

This article from veterinary medicine gives instructions on various neurological exams including testing the postural responses. Scroll down to number 4. We’ll discuss the importance of postural reflexes below.

History

We have Pavlov to thank for part of the confusion about the opposition reflex. Pavlov came up with the term “freedom reflex” for the escape behaviors of a dog who strongly resisted the harness he used in his laboratory. He generalized it to all organisms. (It turns out that Pavlov liked to call all sorts of things reflexes. That is a whole other discussion.)

Most scholars agree that Pavlov grossly over-generalized from the actions of the dog, and was mistaken in calling what was essentially resistance to coercion as a reflex. As one of his critics states:

There is of course no reflex of freedom, although it is easy to see resistance to coercion in animals and humans. Herding cats is nearly impossible, and it is equally hard to keep male dogs from sniffing females in heat. Wild horses resist taming, and most animals cannot be domesticated at all. Human beings fiercely resist unwanted control. But struggling against coercion is not a reflex — it is nothing like a simple atom of behaviour.

(Baars, 2003)

Pavlov’s so-called freedom reflex consists of much more varied behavior, sometimes chains of behaviors, which comprise methods of escape or regaining balance. These behaviors vary to the extreme by species and individuals. A large, gentle animal might just walk away if you tried to restrain it without any special equipment. But anyone who has ever tried to handle feral kittens knows that their methods of trying to escape are typically painful and actually dangerous (because of the possibility of infection from scratches and bites) to humans.

What are typical situations in which an animal might exhibit these compensatory or escape behaviors?

1. The animal is trying to get to something and is being restrained
2. The animal is trying to get away from something and is being restrained
3. The opposite can also occur: the animal is being forced to move and is resisting, as when a trainer tries to force a sit by pushing the dog’s butt down.
4. The animal has been knocked off balance and is trying to regain equilibrium.

(I’m omitting situations where the animal has been trained to create or maintain pressure, such as a roping horse who can hold a line taut, or all sorts of animals that pull sleds or carts.)

Do you see the pattern here? In all cases, the animal is resisting force, confinement, or physical discomfort. When we use the phrase “opposition reflex,” we are often neatly sidestepping the fact that we may be trying to get the animal to do something it doesn’t want to do. It’s a shortcut, a label that unfortunately encourages us to leave out our agency in the matter.

But decades after Pavlov, trainers grabbed onto the concept of the freedom or opposition reflex.

Opposition Reflex and Thigmotaxis

The only mention of the opposition reflex I have found in a scholarly work is an article in The Journal of Equine Veterinary Science (Miller, 1996). It’s one of a series of more than 20 articles. Miller may have been the first to use the term “opposition reflex” and equate it with positive thigmotaxis (I’ll define thigmotaxis below). The examples Miller gave were of a dog pulling back against leash pressure (as in the photo at the top of the page), and the way a cow will push back and lean into you if you try to get it to move by pushing on its side if it is stepping on your foot.

Per Google Scholar, this article has zero citations in other articles. This means that no studies were performed to experimentally validate his claims and no studies have made a reference to his article. (But props to Dr. Miller: in another article he pointed out that shying in horses is a fear response and we shouldn’t respond to it with coercion or pain. He described his approach to it, which was desensitization with the goal of habituation.)

Steven R. Lindsay expanded on Miller’s claim. In Volume 1 of his Handbook of Applied Dog Behavior and Training, he also claimed that the opposition reflex was an example of thigmotaxis. But in Volume 3, he rescinded his recommendation of the term thigmotaxis for response to leash pressure and returned to using the term opposition reflex. It’s pretty clear that his original citing of thigmotaxis was an educated opinion, not based on experimental literature. And he changed his mind.

So what is this thigmotaxis and is it really relevant?

Oxford Reference defines the term thigmotaxis as “Movement towards or away from a solid object in response to tactile stimulation.”

Thigmotaxis is one of several classifications of movement. It is not a reflex. The first reference to it I could find was in an 1897 study called “Studies on reactions to stimuli in unicellular organisms: I. reactions to chemical, osmotic and mechanical stimuli in the ciliate infusoria” (Jennings). Other classifications of movement include electrotaxis, geotaxis , and thermotaxis. These terms refer to directional movement affected by an electrical field, by gravity, and by a heat source, respectively. Note that I am using the term “affected by” because these directional movements may be toward or away from these stimuli.

Thigmotaxis was first noted in paramecia and other microorganisms. Over the years, the term was also applied to invertebrates and mammals. Classic examples of positive thigmotaxis (moving toward stimuli) are cockroaches’ behavior of jamming themselves into crevices and rodents’ tendencies to walk staying in touch with walls and other vertical surfaces. Negative thigmotaxis is a movement to avoid certain stimuli, and is seen in fish and unicellular organisms.

Positive thigmotaxis (turning **toward** touch or pressure) is seen in neonate puppies in the behavior of rooting for a nipple. Other than that, I haven’t seen it listed as present in dogs.

Again, this is a little of a side trip, since thigmotaxis is not classified as a reflex.

When Is the Opposition Reflex Discussed in Dog Training?

The so-called opposition reflex is generally brought up in discussions about leash walking, molding behaviors, and play.

Leash Walking

Countless writers highlight a dog’s supposed opposition reflex when discussing why a dog won’t yield to leash pressure, but instead, might pull the other way. Reducing the reasons a dog might not yield to leash pressure, or will take action to create it, to an “opposition reflex” is simply applying a label. It gives us no insight into the situation. Many writers grab onto the phrase without considering the many sources and reasons for this behavior.

Training by Molding Behaviors

Another place you read about the “opposition reflex” is in discussions of molding as a training technique. This is not a method that positive reinforcement-based trainers use, but it bears mentioning because people who do use it bring up the opposition reflex. It’s found in the old “push the dog’s butt down to teach him to sit” method. If you’ve ever tried it, you’ve probably experienced what people call the opposition reflex. It is an instant resistance by the dog to being pushed. It’s very common. It is resistance to being thrown off balance and/or coerced. But again, labeling it “opposition” can even make it sound like this resistance is naughty or defiant.

Play and Restrained Recalls

A final situation in which people discuss the opposition reflex is in activities that involve drive and enthusiasm. For instance, some agility trainers use what are called “restrained recalls.” A partner restrains the dog while the handler calls her. The dog’s push to escape can result in a faster recall when she is released.

Note that the latter situation matches my description #1 above: the dog is trying to get to something and is being restrained. If you have a play history with your dog, this can be fun for the dog. But it’s pretty obvious it’s not a reflex—they are trying to get to something.

Here’s an example where I am restraining my dog in a training/play situation. Check out 0:26 in the video.

I contend that Summer’s pushing against my hands as I pull her backward is not a reflex. We’re seeing a dog who wants to run forward and get to the garden hose.

What Is Really Happening, if Not the “Opposition Reflex”?

I do understand why people call the behavior in the photo at the top of the page reflexive. It can happen so fast! And I know what it feels like to be on the other end of that leash. The dog’s reaction can feel reflexive to us. But it’s a combination of responses.

If I pull or push on a dog, there are certainly reflexes triggered in the dog. There are a number of postural reflexes that help animals stay on their feet or in another position. The first things that happen in this situation are reflexes such as the stretch (myotatic) reflexes, the righting reflexes, and/or the vestibulo-ocular reflex. These reflexes combine to keep the dog on its feet and balanced via various muscle movements. As these reflexes happen, the dog does not likely look like the dog in the photo at the top. Not yet. We might not even see the balance compensations these reflexes cause, as they happen milliseconds after the push or pull.

But right on top of the respondent behaviors involved with balance come operant behaviors. As I pull or push and the dog’s reflexes help them to keep their balance, what happens next? It depends on how hard I pulled or pushed, a hundred other items in the environment, and the dog’s emotional state and motivators at the time. The dog might yield to pressure and come along, or the dog might try to stay still, move in the other direction, or even lie down in an effort to not come with me. (Imagine some fearful dogs being dragged into the vet’s office.) These are operant responses that are helped along, in some cases, with the postural reflexes. Remember, the goal of these reflexes is to keep the dog from falling over, not to “oppose” us humans.

A final argument: if the “opposition reflex” were real, we wouldn’t be able to significantly alter it with operant training plans. Yet we do that all the time!

Summary: What’s the Problem With the Phrase?

I think we should question our use of the phrase “opposition reflex” because:

• It’s a label—it can stand for dozens of different behaviors.
• The behaviors it is used to describe are generally not reflexes.
• It discourages us from analyzing and asking why the behavior is being performed. (E.g., the leashed dog simply wants to go faster.)
• It discourages us from looking at our role in setting the stage for the behavior.
• It discourages us from determining the consequences that are driving the behavior.
• It sounds automatic, non-volitional.
• It also sounds negative. Opposition sounds like defiance.
• It defines the dog in terms of compliance, not acknowledging that their desires and responses are valid.
• It promotes confusion about respondent and operant behaviors.

Positive reinforcement-based trainers don’t usually take an oppositional stance, and we don’t usually attribute one to dogs. To me, it seems much more helpful to understand that the dog is wanting to go at a different speed or to a different location than to reduce it to “opposition reflex.” The “opposition” part can make them sound downright contrary, instead of being creatures with their own agency and interests. In addition, the “reflex” part obscures that their behavior may be a visible indication of what they want or intend. Reflex sounds like they pull because they can’t help it, not because they are motivated by something.

I don’t think the term is going away anytime soon. But I hope we can get better at actually observing and describing behavior and understanding its causes and consequences. If we did that, this term would be left behind.

Have you heard the phrase in more contexts that I have listed? Have you ever seen a true reflex mentioned when discussing the opposition reflex?

“Opposition Reflex” Challenge

When I first published the earlier version of this post, I got a lot of pushback. So I issued this challenge. So far, no one has come forward. But here it is again.

To anyone who wants to claim that the opposition reflex in dogs is a true reflex/respondent behavior, the burden of proof is on you. I have tried and failed to find evidence for any of those. If you succeed, I’ll retract appropriate statements and amend my post. To provide evidence, l believe you should do the following:

• Cite a source listing the “opposition reflex” by name as a true reflex from a canine anatomy/physiology, neurology, or another veterinary textbook.
• Show that near 100% of neurologically healthy dogs demonstrate it in the same way and that the physiological response is consistent.
• Name the body part that can receive the stimulus and the nerve group involved.
• Show that it can’t be punished or reinforced. This is a characteristic of respondent behaviors.
• BONUS: Show that veterinarians have a test for it.

As I mentioned, I have already tried and failed to find these things. Please let me know if you find them.

References

• Alters, S. (2000). Biology: understanding life. Jones & Bartlett Learning.
• Baars, B. (2003). IP Pavlov and the freedom reflex. Journal of Consciousness Studies, 10(11), 19-40.
• Jennings, H. S. (1897). Studies on reactions to stimuli in unicellular organisms: I. reactions to chemical, osmotic and mechanical stimuli in the ciliate infusoria. The Journal of physiology, 21(4-5), 258.
• Lindsay, S. R. (2000). Handbook of applied dog behavior and training: volume one, adaptation and learning. Iowa State University Press.
• Lindsay, S. R. (2013). Handbook of applied dog behavior and training, adaptation and learning (Vol. 1). John Wiley & Sons.
• Miller, R. M. (1996) The Opposition Reflex. Journal of Equine Veterinary Science Volume 16, Issue 8, 324-326.
• Pavlov, I. P. (1928). The reflex of freedom. In I. P. Pavlov & W. H. Gantt (Trans.), Lectures on conditioned reflexes: Twenty-five years of objective study of the higher nervous activity (behaviour) of animals (pp. 282–286). Liverwright Publishing Corporation
• Today’s Veterinary Practice. “How to Perform a Neurologic Examination in Companion Animals.” January/February 2013. Retrieved from https://todaysveterinarypractice.com/neurology/the-neurologic-examination-in-companion-animals-part-1-performing-the-examination/

Copyright 2023 Eileen Anderson

Photo Credits: © Can Stock Photo Inc. Vishneveckiy and Anke (the two leashed dog photos
Wikimedia Commons user Harold Meerveld (the bikejoring photo) under this license